Electric signal encoder



Jan. 26, 1954 P. MANUEL ELECTRIC SIGNAL ENcoDER 2 Sheets-Sheet 1 Filed May 3l, 1951 4 Jan. 26, 1954 P, MANDEL 2,667,633

ELECTRIC SIGNAL ENCODER Filed May 5l, 1951 2 Sheets-Sheet 2 FIGA? Patented Jan. 26, 1954 attain ELECTRIC SIGNAL ENcoDER.

Paul Mandel, Paris, France, assigner to` La Radio- Industrie` S. A., Paris, France, a corporation of France ApplicationfMay 31,1951, Serial No. 229,049 Claims priority, application France .I une 14, 1950 10 Claims. (Cl. 340-354) TheA present invention relates to encoders of electric signals of the kind in which a train of periodic number representing pulses is delivered each time an actuation signal', generally a single electric pulse, is applied on their input. In such encoders, any coded train represents, by presence and absence of concrete pulses in its code ele'- ments; theA sequence of the coefli'cients of the arithmetic development of aV number expressed in theV so-calledbinary' system of numeraticn, that is the system of numeration having' the ligure 2V taken as radix; In its general form, such a development is:

ao-Fa1.2-|-a2.22! |,-a'n1.2111 for-'the writingl of; any number' between zero and 2.11-1. Th'e-coeicients:amar, ai', aan can only receive one ofv the two values 0 and 1, and the Writing particular toy a, given' number of a value' comprised between 0 and 211-1' is obtained by ascertaining an appropriatev repartition of said values" 0 andA 1 to the various coefficients.

The inventiony related more specically to encoders of the kindin which all theY electrical codes of numbers comprised between zero and v 2,15 are) present. in a` circuit arrangement which includes, in its input and (or) itsoutput, means for selectivelyl delivering acoded tra-in of. num= ber representing, pulses.l corresponding. toV anV elected valuee of numberiwhenv. an actuationl pulse, o'ff aY duration at most equal to. the.V durationA ci. a. code element of the train, is applied on its input.

One object.A of. the. invention is to. provide certain embodimentsof such encoders which,y being` easy to design. and. adjust, canbe. operated. with.

a very high rate of code elements.when-required.. A further object ot the :invention` isto provide said. embodiments. of. encoders such that they canbe actuated either inv a rhythmic. or in an.

arhythmic modeof control, whilst. always delivering a coded pulse train of rhythmedor recurrent code. elements. according; to. whether they are designed for the encoding, of initiating pulses applied at. random intervals ofl time on their inputs, said intervals being though always higher thanthe maximum duration of any coded train to bel delivered,y or they are designed for the encoding of a series of` amplitude-modulated pulses. sampled. from a permanent amplituden modulatedn signal at recurrent intervals equal to or higher than the maximum duration of any codedil train to be delivered. the. maximum. orderg of the development above,

the maximum duration of. such a coded train is.

n0', ifi@ i's the individuall duration of a code ele,-

When (1t-1), is'

ment, as a train of ('n-D order has n codel elements.

In the following description, for the sake of simplicity, the maximum order n-l toy be' considered will be 2, corresponding to developments of three terms: aO-l`-a1.2{a2.22, so that the coded pulse trains concerned will have a maximum duration of 30, as they` present three code elements or moments. Any extension to a high-l er number of terms or code elements will' appeary evident by merely adding encoding channels orl stages in the described encoders, until thev required numerical capacity is reached'.

Encodersv according tothe present invention, and means for actuating same, will be fully described in relation to the attached drawings, inwhich:

Fig. 1. shows'a diagram of electric signals for explaining the operation of' said encoders.

Fig. 2 showsv the basic circuits oi encoders as providedv in the invention,

Fig. 3 shows a block schematic arrangement of said basic circuits in which encoding channels are maintained distinct, y

Fig; 4 shows a schematic arrangement of a complete circuit for. encoding av permanent signal. in which is incorporated'y the encoder of' Fig. 3and,`

Figs. 5, and 6 show two alternative block schematic. arrangements derived from the arrangement of Fig. 3, from. a contraction of. theY encoding channels in a single cascade connection of the basic circuit stages.

The above mentioned restriction to three code elements for the trainsy to be generated, of a maximum duration T=39, limits the coniiguration of the sevenl code signals toY those indicated under references ll to 1 in Fig. 1. The remaining signal, being' zero, is not considered as it comprises merely al total absence of pulse at the threecode'elements.

These codedv signals, from l to l, are generated by encoding a single pulse such as 8, Fig; l, applied at the inputv of the encoder, for instance at instants separated in time by theV interval T. The selection of the said pulse 8 may be provided as it will be described further, either by applying said pulse 8l on a particularized input terminal of the encoder, or by applying said. pulse 8 on all inputs but applying then. a selection signal of T duration, such asv 9, Fig. 1,. onv a particularized output terminal of.v the encoder concerned.

An encoder according to. the. present. invention is broadly characterised., in thatfthe. basic encodtrigger stages having a single stability condition. Such stages are often called single shots or one-shots multivibrators in the usual technical literature, and also monostable trigger stages which designation will be used throughout the present description. Such monostable trigger stages can be designed as indicated at I and II in Fig. 2. Considering stage I, a double triode tube IB has one of its grid connected to an input terminal I I through an input coupling circuit I2-I3. I2 is a series capacitor and I3 a biasing resistor. 'Ihe plate of this triode element is connected to the high voltage direct current supply through a delay line I5 and a resistor Irl. The delay line I5 is short-circuited at one end, as indicated at I5. The ground cathode-bias I1 is common to both triode elements. The second triode element has its control grid biassed at I8 and connected through the capacitor I9 to the plate of the iirst triode element. From the plate circuit of .said second triode element, is taken, through the capacitor 20, the output conductor 2 I.

The operation of such a monostable stage, well known per se, may be explained as follows: at rest, the iirst triode element is on, the second is ofi'. When an incoming signal, of negative polarity is applied at I I, the first triode element is cutoff and the plate impulse of said element, of positive polarity, goes along the delay line I5, is reflected at IS with reversed polarity and comes back. The second triode element has been put in the on condition by the pulse from the plate of the first, direct through capacitor I8. The ren flected pulse, then, when returning to the plate, is applied in its reversed polarity, and its own delay, to the grid of the second element which is put in the off condition again, the first element being then brought to the on condition. The stage has thus rocked twice by the application of a single input pulse, and has thus delivered in the output conductor 2! an electric pulse the duration of which is defined by the transit time to and fro of the delay line I5 A similar result can be obtained by replacing the delay line I5 by a lumped constant RC circuit, though with a lesser precision of stroke. The bias connection may be so made as to obtain an inverted operation, the rest condition of the stage being then given by the o vcondition of the rst triode and the ofi condition of the second, the actuation pulse and the delivered pulse being then of inverted polarity as to the given example.

The length in time of the output pulse at 2I is then given by the length of delay line I5 :from its input to the short-circuit Iii and back. If said length is taken equal to 0, the monstable trigger stage when actuated, will generate a signal such as I, Fig. 1. Ii this length is taken equal to 20, it will generate a signal such as 3, Fig. l, and if this length is taken equal to 39, it will generate a signal such as 1, Fig. l. In other words, the reading by an incoming pulse, of the value of delay in I5 will cause the generation of coded signals representing the numerical values 1, 3 and 7, according to the magnitude of delay of line I5.

In order to generate signals such as represented at 2, Il or E, Fig. 1, featuring the numbers 2, 4 and 6, which signals are characterised by an initial delay before the appearance of a voltage amplitude, it is then provided to connect an additional rocking stage, II, of the same kind, in cascade connection with. the first, I. Such a circuit is also shown in Fig. 2. This second stage II will act as a delay circuit if, between its own output 2l and the actuating point 22 of stage I, a differentiating circuit is inserted, constituted for instance by a sei-ies condenser 23 and a grounded shunt resistor 24. This circuit differentiates, in the mathematical meaning of the word, the output signal at 2 I, stage II, that is to say that, from a single pulse such as I, Fig. 1, let only subsist two sharp pulses, of mutually reversed polarities which denne the instants of beginning and ending of pulse I. The sharp front pulse is clipped by diode 25, plate-blessed at 25, so that the coupling capacitor 21 will only pass towards 22 the sharp rear pulse, delayed by 0 with respect to the front pulse.

If noW, stage II has a delay time of 0, the pulse signal thus generated at the output of stage I is of the shape indicated at 2, Fig. l. If stage II has a delay time of 20, the puise signal thus generated at the output of stage I has the shape indicated at 4, Fig. l. In both cases, stage I is provided with a delay time of 0.

If, on the other hand, stage II is provided with a delay time of 0 and stage I with a delay time of 20, the signal at the output of stage I will be such as indicated at 6, Fig. 1.

If now, stage II is provided with a delay time of 20, and stage I with a delay time of 0, the simultaneous application of two pulses on both inputs of the two stages will produce an output signal of the shape of 5, Fig. 1.

The derivation of signals of more complex con gurations, corresponding to higher values of numbers may be similarly provided by providing more values of delays and (or) a greater number of monostable stages connected in cascade relation through differentiating circuits.

Having thus deiined the basic circuits of en coders according to the present invention, two kinds of embodiments may be provided. In the rst, as shown in Fig. 3, a number, here seven, of distinct elementary encoders are distributed in seven channels, from 3I to 31. In the second, as will be shown in relation to Figs. 5 and 6, it will suice of three monostable rocking stages, by a mere contraction of the elementary encoders of Fig. 3.

In Fig. 3, the body of the encoder proper is comprised between dotted lines 39 and 40. A common input channel for the application of reading pulses is shown at 28 and channels 3| to 31 may be connected by code selection contact means, as indicated at 291 287, to said input channel 28. These contacts may be cam combining contacts, in an electro-mechanical embodiment, or better, in an all-electronic embodiment, to be further described in relation with Fig. 4, by targets inserted within a cathode ray tube selector.

In alternative, contacts 29 may be omitted or closed and the code selection for the output common channel 30 may be made through output selecting contact means, from 381 to 387, of the same kind as means 29.

In the rst case, contacts 29 need to be closed during an interval of time no longer than 0; in the second, contacts 38 need to be closed each time during an interval of time equal to T.

Channel 3| embodies a single monostable stage I of delay time 0, delivering the signal representing the numerical value l. Channel 32 embodies a monostable stage 42, of delay time 0, followed by a second monostable stage 49 through a dierentiating circuit 138, said second monostable stage 49 having a delay time 0. thus delivering the signal representing the numerical value 2. Channel 33 embodies a single monostable acercaba:

stage. 43;. of delayltime 2e: deliveringy thea signal representing the: numerical value. 3; Channel 34:. embodies; ai. first monostablestage; 442 of dela-y time 29; then, through a.. diierentiatingl circuit 50, a second monostable stage 5! of.` delaytimev a, thus; delivering; the signal representing the numerical: value Channel 35. is; divided into twdbrancheatharst. embodying; ai single mona` stable. stage 45.E of.`- delay time the. second: in.- cascade. connection. through diilerentiating..cire` cuit 5.5;, twof monostable stages 55. and: the stage 55: having a delay time ofl 2e and: the sec-A ond; a. delay time'. of 0',- thusdeliv'ering at: 5a the signa-la representing' the numerical value 5; Channel. 3S embodies: a -rst monostable stage 46; of delay time 0l, followedi through a diner--J entiating circuit'. 52;, byf a monostable stage 53 of' delay' time 20; thus; delivering they signal repre-i sent'atvefoti the numerical value Si. Channel 3f? embodies a single monostable stage 4T of delay time 30, thus deliveringtheisi'gnalrepresentative of the numerical value '75.

encoder arrangement such as in Fig; 3i is particularly fitted to` operate in association' witha sampling arrangement for encoding a permanent or continuous signal ofd variable amplitude; forinstance for encodinga videotelevisionl signal".

Fig. 4"- shows such a combination ofV means. Each' channel ofthe encoder oi Fig. 3', the body of which is indicated' as a whole at 63 in an illus-v trati-ve delay representation, in connected', throughA a casual amplifier stage 52, to a target 219- included in a cathode ray tube 59L the` beam of-'w'hichI is controlled by the pulse sampling generator 60, of pulse recurrence T. One deiiector circuit of said tube, for instance a single pair of' deilecting plates, is driven by an" amplitude'- modulated continuous'` signal issuing fromV an ampl'ier' 61 and being for'example, a video tele--v vision signalI pickedk up at then output of a. television, camera of any kind;

In such an arrangement', at each instant ii of" the period T; Fig; La pulse will be generated on; one of the; targets 29v according to the. instantaneous amplitude level of the video signal and.

this pulse will: pass through the corresponding encoder channel so that it will appear at 3U in the shape of' the corresponding coded signal. The; cathode. ray tube fulfills both functions of measuring the signal strength and connecting the selected chan-nel of the encoderfto the input pulse arrangement. In tube 53 is indicated an additional target 54; which is; proyidediA for in;- di'cating zero., or less. than unity, amplitude level, where nov output. signal to. be delivered by the.- encoder.

A; single coupling thus exists. between each targetv and; eachencoding channel; Further, the time constant to establish the signal triggering the input stage of each channel may then be made very small and, obviously, such an arrangement can ensure very high speeds of encoding.

When a greater time constant may be allowed, however, it then becomes of interest to restrict the number of monostable stages used in the encoder. Thus, one can consider embodiments such as in Figs. 5 and 6, in which only three monostab-le stages, cascade-connected through 4 two intermediary differentiating circuits are only used. These stages are referred as t5, $5 and` t1, and their time constant is uniformly taken equal to 0. The differentiating circuits are referred as 58, between stages 65 and 5t, and t@ between stages S6 and S1. Stage 61, in Fig. 5 may be, ii' required or wished, taken With a delay time each off the` seven code 5. lesser than 0, so' as. to separatepulses more definitely in. the output signals.

Referring to Fig; 5, the individual inputs` of stages 6.5, i561 and. El, referred. tol as- 'Hi and l2; respectively, of' an input mixer, shown: under the formV ot a resistor mixer.I but in which each resistor maybe-replaced by thedischargelpatlr ofi a vacuum or gas tube. Said inputV mixer" may be enteredy in by a reading or initiating pulse by selection terminals 3l to`l 37.'. Each of said terminals maybeconnectedf to a target 2.9i oi' a sampling and qualifyingJ cathodeiray tube, as in Fig. 4;' said tube receiving for" instance a. facsimile or telephone signal.

The operation of the arrangement of Fig. 5 becomes evident when following the paths from-` ans7` input terminal to the output conductor- 3U; with` no diierencewith. respect to that oi? Fig; 3; when contact inea-ns 38 are omitted andthe codeselectionvr operated from contact means 2-9.

Iny the alternative arrangement of Fig. 6; they progression of the pulses in the cascadeY of' stagesis reversed, a common input channel being. provided for the actuation of stage 6l, by recurrentl pulses. The codedtrains of all they numerical values from 1 to 7 are thus generated' each time* an initiating pulse enters at 6u. The output mixer issimilarly made as the inputr mixer of Fig. 5, and its points ll, 18 and 19 are respectively connected to the individual outputs T4, 'l5 and 'i6' of stages B1, 65 and 65; The output terminals of' the miner, referred to as $1 viduallly connected to grids oi vacuum multi-grid tubes S-I to 91, the` platesv of which are connected in common to the outputv conductor 30- ol? the encoder. These grids may bev for'instance thecontrol grids of tubes 9i' to 91 or theyl may be conversely suppressor; on other grids of saidtubes, Suppressorsy ory control grids, are applied selection code pulses. at terminals 3|; 11u31", one se-vlection pulse at aftime, of` dura-tion T, soA that one only of said tubes isplaced in the on. condition` and transmits the coded signal" applied at thev output terminal of' the miner 113 to which it isY related;

The terminals 3i to 3l, can here again, be c0nnected tol respective targets of a measuring and sampling cathode ray tube.

Ifclair-n:l

In anv encoding device for transmittingbinary` code combination representing numbers from', zero-to` a maximum value 211e wherein the maxi'- mum: duration T of a code combination isI nu', where @risy thefdura-ticn of an individual code ele ment, the combination of a 2114 channels, eachY oi'l said'channels includ-ing at leastv onev one-shot multivibrator delivering a pulse having a minimum time duration of H, at" least oney of said channels includingy a diif'erentiating circuit connected to the output of its oneshot multivibrator, a limiter device for transmit ting only the second sharp pulse produced by said differentiating circuit, and a second one-shot multivibrator included in said one channel and controlled by said limiter device.

2. An encoding device according to claim 1 wherein said channels are connected to a common output circuit, and including means selectively applying to the inputs of said channels actuating pulses separated by the interval T, said actuating pulses being of short duration with respect to said interval.

3. An encoding device according to claim 1 wherein said channels are connected to a common input circuit connected to a source of actuattof 31", are indi'-A circuit comprisingv ing pulses separated by the interval T and being short relative to said interval, and including means for selectively connecting the outputs of said channels to a common output circuit.

4. In an encoding device for transmitting binary code combination representing numbers from zero to a maximum value 2n1 wherein the maximum duration T of a code combination is 11.0, where is the duration of an individual code element, the combination of a circuit comprising 2-1 channels, each of said channels including at least one one-shot multivibrator delivering a code pulse having a minimum time duration of 0, certain of said channels including only one multivibrator and delivering pulses having durations which increase progressively by intervals of 0 from one channel to another, at least one other channel including a diierentiating circuit connected to the output of its multivibrator, a limiter device connected to said dierentiating circuit for transmitting only the second sharp pulse produced by the differentiating circuit, and a second oneshot*l multivibrator controlled by said limiter device.

5. An encoding device according to Vclaim l wherein one of said one-shot multivibrators is common to all of said channels.

6. An encoding device according to claim l wherein n multivibrators are connected in cascade, the output of each multivibrator in the series being connected with the input of the succeeding vibrator through a diierentiating device and a limiting device to transmit only the second sharp pulse generated by the differentiating circuit, and said channels being completed through diierent combination of said multivibrators.

7. An encoding device according to claim 1 and including a common output circuitffor said channels, separate input terminals for said channels, a single deflection cathode ray tube, means for controlling the deflection of the beam of said tube by an amplitude-modulated signal, means for controlling the on-oi condition of said beam by a series of recurrent pulses, a series of targets within said tube and spaced along the path of deflection of said beam, said targets being connected respectively to the input terminals of said A channels.

8. An encoding device according to claim 1 and including a common input circuit for said channels, means for applying simultaneously initiating pulses on said input circuit, an electron tube on-off switch in the output of each channel, a common output plate connection for said tube switches, a cathode ray tube having a single beam deflection arrangement, means for controlling the deflection of the beam of said tube by an amplitude-modulated signal, means for controlling the on-off condition of said beam by a series of recurrent pulses, a series of targets within said tube and spaced along the path of deflection of said beam, said targets being connected respectively to the control electrodes of said electron tube switches.

9. An encoding device according to claim 1 wherein said multivibrators are connected in cascade connection through differentiating-clipping circuits, an input mixer having as many output terminals as there are multivibrators in the cascade connection, and having as many input terminals as there exist numbers from 1 to 2li-1, a cathode ray tube having a single beam deflection arrangement, means for controlling the deection of the beam of said tube by an amplitude-modulated signal, means for controlling the on-of condition of the beam by a series of recurrent pulses, a series of targets within said tube and spaced along the path of deiiection of said beam, said targets being connected to the respective terminals of said mixer.

10. An encoding device according to claim l wherein said multivibrators are connected in cascade connection through differentiating-clipping inter-stage circuits, means for applying on the input of the rst multivibrators a series of recurrent pulses, an output mixer having as many input terminals as there are multivibrators in the cascade connection, and having as many output terminals as there exist numbers from 1 to 211-1, electron tube switches having each one grid connected to one of said output terminals, a cathode ray tube having a single deflection arrangement, means for controlling the deilection of the beam of said tube by an amplitude-modulated signal, means for controlling the on-off condition of said beam by a series of recurrent pulses, a series of targets within said tubes and spaced along the path of deflection of said beam, said targets being connected each to a second control grid of said electron tube switches, the recurrence of the two series of pulses being the same, the series of input pulses of the cascade connection being of duration lower than the duration of a code element and the duration of beam controlling pulses being equal to the maximum duration of the coded signal corresponding to the 2-1 value.

PAUL MANDEL.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,409,229 Smith, Jr. et al. Oct. 15, 1946 2,424,481 McCoy July 22, 1947 2,461,110 Fischman Feb. 8, 1949 2,534,369 Ress Dec. 19, 1950 2,567,846 Jacobsen Sept. 11, 1951 2,577,141 Mauchly et al. Dec. 4, 1951 

